Chapter 5. Considerations During the Manufacturing Phase

During the manufacturing phase of the life cycle, the plastic granulates are made into a product part. Common chemical types used in the process are raw materials, monomers, oligomers, catalysts, polymers, performance additives (e.g. anti-oxidants, colorants, plasticisers, UV stabilisers, flame retardants, compatibilisers, etc.), and manufacturing and processing aids (e.g. lubricants, anti-block and slipping agents, and antistatic agents). Several considerations need to be taken into account throughout the manufacturing phase:

  1. A. Select a manufacturing technique that:

  • generates the least emissions.

  • uses the least processing aids.

  • uses non-hazardous or the least hazardous chemicals.

  • minimises worker exposure.

  1. B. Consider sustainable manufacturing on a systems level.

  2. C. Ensure transparency in chemical composition throughout the value chain.

In this section, the considerations for the manufacturing phase are further explained.

  1. A. Select a manufacturing technique that:

  • generates the least emissions.

Manufacturing plastic products can generate various emissions. “Waste” streams throughout this phase of the life cycle should be kept in the loop and at least recycled into another material. Emissions that cannot be kept in the loop should be specified (e.g. CO2, methane, and emissions harmful to human health and the environment). Tools to assess emissions during lifecycle phases are described in Annex A: Overview of Relevant Methods, Tools and Metrics.

Consider the emissions calculated with life cycle analysis for diverse manufacturing techniques to compare them. Consult the OECD case study on detergent packaging to learn more about the sustainability of extrusion blow moulding compared to injection stretch blow moulding (OECD, 2021d).

  • uses the least processing aids.

Find a manufacturing technique that minimises the variety of types of chemicals and their quantity required to abate the consequent environmental pollution and human exposure. Moreover, consider the energy consumption (i.e., amount and source of energy), water consumption and overall waste produced to compare manufacturing techniques.

Questions to ask suppliers and producers: What chemicals are used as processing aids and in what quantity? Are the facilities tracking their emissions and their energy, water, and material use? Have they set goals to reduce these?

  • uses non-hazardous or the least hazardous chemicals.

Consideration of chemical hazards are key when designing sustainable plastic products. Chemicals needed during the manufacturing processes and that will be present in the finished plastic article should first be identified. Their hazards and particular properties (e.g. persistency or mobility in the environment, potential to bioaccumulate) should assessed. Use of chemicals that are, for example: carcinogenic, mutagenic, or toxic to reproduction (CMR), Persistent, Bioaccumulative and/or Toxic (PBT), very Persistent and very Bioaccumulative (vPvB), Persistent, Mobile, and Toxic (PMT) or are of other concern, such as Endocrine-Disrupting Chemicals (EDC) should be avoided.

The use scenarios for a product define the requirements for manufacturing techniques, as well as all the other life cycle phases. With products that come into close contact with food or skin (e.g. food packaging, toys) particular efforts are warranted, such as not using any hazardous substances.

  • minimises worker exposure.

Consider what exposure scenarios are to be expected during the manufacturing processes studied.

Prioritise consideration of occupational and environmental exposures to hazardous chemicals, and toxic emissions and waste. Comparative exposure mapping helps to pinpoint potential exposure pathways. Qualitative exposure assessments can be based on the presence of chemicals in a form that can be inhaled, ingested or absorbed through the skin during the manufacturing of the product part.

  1. B. Consider sustainable manufacturing on a systems level

It is important to take into account the environmental impacts associated with the manufacture and distribution of products. For example, if a product consists of different parts that are to be mounted together, consider a physical design of parts to avoid the need of glue. By such design choices, additional chemicals can be avoided and the product will more easily be reused or recycled. For transport, consider the distance between the manufacturing facility where product parts are made and the location where they are assembled or completed (e.g. filling a bottle of detergent). Ideally, these processes occur at the same location, with limited distance to retailers. When this is not possible at the same location, another manufacturing technique could be considered. For instance, it is recommended to assess the environmental impact of transporting empty bottles to be filled versus reheating preforms for injection stretch blow moulding on location.

Question to suppliers or manufacturers: what measures are in place to track and report key sustainability measures?

  1. C. Ensure transparency in chemical composition throughout the value chain.

To support informed decision-making concerning the chemicals used in manufacturing, transparency is important to identify what is known and where data gaps lie. A tiered and iterative approach to chemicals inventory could be used (i.e., “starting with higher disclosure thresholds, and working to gather additional information at lower thresholds as feasible and relevant”).

For example, the Global Automotive Declarable Substance List (GADSL) can be used to assess substances expected to be present in automotive products through the supply chain.

References

ECHA. (n.d.). Substances of concern: Why and how to substitute? European Chemicals Agency, Helsinki, Finland, https://echa.europa.eu/documents/10162/24152346/why_and_how_to_substitute_en.pdf/93e9c055-483c-743a-52cb-1d1201478bc1

OECD (2021), “Guidance on Key Considerations for the Identification and Selection of Safer Chemical Alternative”, Series on Risk Management, No.60, OECD, Paris, https://www.oecd.org/chemicalsafety/risk-management/guidance-on-key-considerations-for-the-identification-and-selection-of-safer-chemical-alternatives.pdf

OECD (2021b), “Case Study on Insulation: An example of chemical considerations for sustainable plastics design”, Series on Risk Management, No.66, OECD, Paris.

OECD (2021d), “Case Study on Biscuit Wrappers; An example of weighing sustainability criteria for plastic flexible food packaging from a chemicals perspective”, Series on Risk Management, No. 64, OECD, Paris.

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